1. Preheat the oven to 425° F. Place a rimmed baking sheet in the oven while it preheats.

2. Toss the vegetables with olive oil, vinegar, and seasonings in a large mixing bowl. Remove the hot baking sheet from the oven and spread the vegetables out in a single layer on the sheet. Place in the oven and roast for 15 minutes.

3. Spread the buttery spread on one side of all four slices of bread. A few minutes before the vegetables are done roasting, place a heavy-bottomed skillet on the stovetop over medium heat. Place two slices of bread (buttery-side down) in the skillet. Spoon the mayo and mustard evenly on each slice and use the back of the spoon to spread it. Divide the cheese slices between the sandwiches and spoon the hot roasted vegetables on top of the cheese. Add optional ingredients if using and the second slice of bread, buttery-side up. Cook until lightly browned on the first side, about 4 minutes. Carefully turn the sandwich and cook on the second side until browned and the cheese is melted, about 4 minutes.

4. Serve immediately with soup or salad.